Twistronics for photons: opinion

Uncertainty relation for photons.

The uncertainty relation for the photons in three dimensions that overcomes the difficulties caused by the nonexistence of the photon position operator is derived in quantum electrodynamics. The photon energy density plays the role of the probability density in configuration space. It is shown that the measure of the spatial extension based on the energy distribution in space leads to an inequa...

Search for photons with

A search for ultra-high energy photons with energies above 1 EeV is performed using nine years of data collected by the Pierre Auger Observatory in hybrid operation mode. An unprecedented separation power between photon and hadron primaries is achieved by combining measurements of the longitudinal air-shower development with the particle content at ground measured by the fluorescence and surfac...

Opinion Opinion Opinion

A common notion of vision, consistent with this excerpt from the first paragraph of David Marr’s seminal book [1], is gained by considering the predicament of a person with a searchlight placed in a pitch-dark room full of unfamiliar furniture. One would hope that, by swinging the beam around, the observer will be able to recognize the objects present in the room (a cat here, an aquarium there,...

Superfluid state for photons

Searching for Dark Photons

Researchers have studied electron-positron (e+e-) collisions for interactions that produce a normal photon γ and a dark photon A′ that interacts with ordinary matter particles. The dark photon can potentially decay into an e+epair (shown here) or a μ+μpair (not shown). However, the latest results from the BaBar collaboration offer no sign of dark photons, thus placing new limits on these types ...